Technetium has been identified as an element of interest for the safety assessment of a deep geological repository for used nuclear fuel. In this study, the sorption of Tc(IV) onto MX-80 bentonite, illite, and shale in ionic strength (I) 0.1–6 mol·kgw−1 (m) Na-Ca-Cl solutions at pHm = 4–9 and limestone at pHm = 5–9 was studied. Tc(IV) sorption on MX-80 increased with pHm from 4 to 6, reached the maximum at pHm = 6–7, and then gradually decreased with pHm from 7 to 9. Tc(IV) sorption on illite gradually increased with pHm from 4 to 7, and then decreased as pHm increased. The sorption properties of Tc(IV) on shale were quite similar to those on illite. Tc(IV) sorption on limestone slightly increased with pHm from 5 to 6 and then seemed to be constant at pHm = 6–9. Tc(IV) sorption on all four solids was independent of ionic strength (0.1–6 m). The 2 site protolysis non-electrostatic surface complexation and cation exchange model successfully simulated the sorption of Tc(IV) onto MX-80 and illite and the optimized values of surface complexation constants were estimated.

Technetium-99 is identified as an element of interest for the safety assessment of a deep geological repository for used nuclear fuel. The sorption behavior of Tc(IV) onto MX-80 and granite in Ca-Na-Cl solutions of varying ionic strength (0.05–1 mol·kgw−1 (m)) and across a pHm range of 4–9 was studied in this paper. Sorption of Tc(IV) was found to be independent of ionic strength in the range of 0.05 to 1 m for both MX-80 and granite. Sorption of Tc(IV) on MX-80 increased with pHm from 4 to 7 and then decreased with pHm from 8 to 9. Sorption of Tc(IV) on granite gradually increased with pHm from 4 to 8 and then became almost constant or slightly decreased with pHm from 8 to 9. A 2 site protolysis non-electrostatic surface complexation and cation exchange sorption model successfully simulated sorption of Tc(IV) on MX-80 and granite. Optimized values of surface complexation constants (log K0) are proposed.

The sorption of Eu on MX-80 bentonite in Na–Ca–Cl solutions is investigated at a molal proton concentration (pHm) range of 3 to 10 and an ionic strength (I) range of 0.1 to 6 m (mol·kgw−1). The sorption equilibrium of Eu on MX-80 is achieved within 14 to 21 d at I = 0.1 and 6 m. The sorption distribution coefficient (Kd) values of Eu for MX-80 increase as pHm increases from 3 to 6 for all I values, and they are independent of pHm between 8 and 10 at I ≥ 0.5 m. Meanwhile, at I = 0.1 m, the Kd value at pHm = 10 is slightly lower than those at pHm = 8 and 9. The Kd values are not affected by the I values between 0.5 m and 6 m, whereas the Kd value at I = 0.1 m is greater than those at I ≥ 0.5 m, except at pHm = 10. A two-site protolysis nonelectrostatic surface complexation and cation exchange sorption model is applied to the Eu sorption data for I ≤ 4 m, and the equilibrium constants of the sorption reactions are estimated.

During the normal operation boron concentrates and spent resins are generated. The boron concentrates are treated by concentrated waste drying system (CWDS) and results in fine powder form. The solidification or application of high integrity container (HIC) is required for the disposal of the dried boron concentrates. The spent resin is stored in storage tank after the water treatment. The spent resin also requires solidification or application of HIC to satisfy the waste acceptance criteria (WAC) in Korea. The solidification process requires periodic validation. The repeated validation and complicated process hesitates the practical application. The application of HIC offers various advantages, including flexible free standing water requirement, higher waste loading compared to solidification, and simple process. The polymer concrete (PC), which is a primary component for PC-HIC exhibits good material stability. The expected transportation mechanism of nuclide in the PC-HIC are 1) diffusion by concentration, 2) permeation by pressure, and 3) capillary suction when considering the disposal condition. Since the PC-HIC effectively prevents the intrusion of neighboring water and volume of free standing water is lower than 1%, it seems that diffusion by concentration is the primary transportation mechanism. In this study, the property of PC is investigated based on Cl ion diffusion test to evaluate the material reliability. The results indicate that PC exhibits superior stability compared to ordinary portland cement. In addition, the reliable life time of PC is estimated base on the element transportation phenomena.

The pH dependence of sorption distribution coefficient (Kd) of Np(IV) on MX-80 in Ca-Na-Cl type solution with the ionic strength of 0.3 M, which was similar to one of the reference groundwaters in crystalline rock, was experimentally investigated under the reducing conditions. The overall trend of Kd on MX-80 was independent of pH at 5 ≤ pH ≤ 10 but increased as pH increased at pH ≤ 5. The 2-site protolysis non-electrostatic surface complexation and cation exchange model was applied to the experimentally measured pH dependence of Kd and the optimized surface complexation constants of Np(IV) sorption on MX-80 were estimated. The values of surface complexation constants in this work agreed relatively well with those in the Na-Ca-Cl solution previously evaluated, suggesting that compared to Na+, the competition of Ca2+ with Np(IV) for surface complexation on MX-80 was not much strong in Ca-Na-Cl solution. The sorption model well predicted the pH dependence of Kd values but slightly overestimated the sorption at the low pH region.

원자력발전소 해체과정에서 방사화 재고량에 대한 평가는 방사선 환경에 정보를 제공함으로써 해체 계획을 수립하는데 중요한 정보를 제공한다. 원자로 운전 정지 후 원자로 및 관계시설에서의 축적된 방사능은 노심 구조물, 반사체 및 차폐체 등의 구조재가 중성자 조사에 의해 방사화된것이다. 방사화생성물 중 36Cl 과 41Ca 은 반감기와 화학적 물리학적 특성에 의해 해체 처 분 관점에서 매우 중요한 핵종이며 이에 따라 본 연구에서는 차폐 콘크리트 내 생성량을 평가하였다. MCNPX 코드를 사용하여 중성자속과 반응단면적을 계산하였으며 이 결과를 토대로 ORIGEN2 코드를 사용하여 방사화생성물의 양을 평가하였다.

목적: 본 연구는 투명 콘택트렌즈와 멀티포컬 콘택트렌즈를 각각 착용하여 원·근거리에서 시력을 측정하였을 때 가입도가 처방된 멀티포컬 콘택트렌즈가 양안시기능에 미치는 영향을 알아 보고자 하였다. 방법: 전신질환이 없고 양안시이상에 문제가 없으며 난시량이 –1.00D 이하인 남·여 15명( 평균연령 21.6±1.5세)을 대상하였다. 자각식굴절검사를 통해 완전교정 상태를 검출하여 일반콘택트렌즈와 멀티포컬콘택트렌즈를 각각 착용시킨 상태와 수정된 모노비전 방법으로 착용시킨 상태로 구분하여 각각 원거리 3m에서 세막대심도지각계를 이용한 심시력 검사와 근거리 40cm에서 입체시(titumus fly) 검사를 실시하였다. 결과: 일반콘택트렌즈를 착용한 상태에서 근거리 입체시력은 79.8±47.5sec이었고 멀티포컬 콘택트렌즈 착용 시 입체시력은 82.8±48.9sec이었으며 수정된 모노비전 착용 시 입체시력은 78.3±36.4sec로 멀티포컬콘택트렌즈 착용 시 입체시력이 떨어지는 것을 알 수 있었다. 그리고 심시력은 일반콘택트렌즈에서 9.58±4.67sec, 멀티포컬콘택트렌즈에서 19.9±12.72sec, 수정된 모노비전에서 6.45±6.32sec로 멀티포컬콘택트렌즈를 착용하였을 때 심시력이 저하된 것 을 알 수 있었다. 결론: 일반콘택트렌즈를 착용하였을 때보다 멀티포컬콘택트렌즈를 착용하였을 때 심시력과 입체시력이 감소하는 것을 알 수 있었다.

The purpose of this study was to measure concentrations of K+, Na+, Cl－ by ionometer with check salt strip, simple salimeter and Ion-selective electrode (ISE) and compare the results of each mensuration; furthermore, the possibility of inferring the Na+ concentration from Cl－ concentration of urine and the impact of K+ on the concentration of each ion was examined. The results showed that ISE determined Na+ and Cl－ concentrations in the urine are highly interrelated (R=0.9039); in addition, concentrations of Cl－, measured with strip and ISE from urine are highly interrelated (R=0.9338). The concentration of Na+ in urine, inferred by measuring Cl－ concentration with strip, has a high relationship (R=0.8580) with the concentration of Na+ in urine, measured by ISE. The results of our study will increase awareness of Na+ intake and the utility of check salt strip, as well as the possibility of inferred Na+ concentration from measures of Cl－ concentration as a screening test for reducing sodium intake.